1. Technical Field
The invention relates to chairs, particularly to supports for armrests of chairs.
2. Related Art
Chairs must be used by everyone every day. Especially, those people who work in offices need to sit on chairs almost all day long. Quality of chairs directly affects feeling of the users. Due to the differences of users' somatotype and habit, besides height adjustment of the cushion, height adjustable armrests are progressively popular in office chairs.
U.S. patent application Nos. 2009/0087251 and 2008/0156962, which were also filed by the inventor of this application, provide two adjustable armrest support structures (hereinafter “'251” and “'962”). These two structures must employ a thumbscrew to position the armrest which has been just adjusted. It is so inconvenient to users. An automatic positioning mechanism will be much more convenient than the conventional such as '251 and '962.